Phase-Migrating Z-Scheme Charge Transportation Enables Photoredox Catalysis Harnessing Water as an Electron Source

Area of Science:

• Photocatalysis
• Green Chemistry
• Organic Synthesis

Background:

• Z-scheme photocatalysis shows promise for converting chemicals using water as an electron source.
• Conventional Z-scheme systems struggle with water-insoluble compounds and overall water splitting.
• Coupling reduction of insoluble compounds with water oxidation is a significant challenge.

Purpose of the Study:

• To develop an unconventional Z-scheme system for photocatalytic conversion of water-insoluble compounds.
• To utilize water as an electron and proton source for reductive molecular conversions.
• To overcome limitations of conventional Z-scheme systems in biphasic solutions.

Main Methods:

• Constructed an unconventional Z-scheme electron transport system with a phase-migrating redox mediator.
• Employed a dichloroethane (DCE)/water biphasic solution.
• Utilized a molecular Ir(III) complex for reductive coupling and Bi4TaO8Cl semiconductor for water oxidation.
• Incorporated ferrocene (Fc) and ferrocenium (Fc+) as electron donor/acceptor with differing partition coefficients.

Main Results:

• Successfully enabled photocatalytic conversion of water-insoluble compounds using water as the electron/proton source.
• Demonstrated selective extraction of Fc+/Fc to opposite liquid phases due to differing partition coefficients.
• Achieved direction-selective electron transport across the organic/water interface via spontaneous phase migration.
• Established step-by-step Z-scheme photocatalysis connecting reduction and oxidation reactions in separated phases.

Conclusions:

• Developed a novel Z-scheme system capable of handling water-insoluble substrates.
• Phase-migrating redox mediators offer a viable strategy for biphasic photocatalysis.
• This approach advances the use of water as a sustainable electron source for chemical synthesis.